You know you're in for a fun evening when your entertainment of choice is being picketed by a grumpy man holding a large plasticated banner proclaiming: "Warning: drunkards, fornicators, masturbators, atheists, abortionists, revellers, sodomites, hypocrites, blasphemers, liars and general heathens – hell awaits you."

The fact that the Rolling Stones can still inspire such ire is not only testament to their legendary rock'n'roll chops, but also proof that a bunch of OAPs can still be dangerous, still be sexy, still be enough to get some sections of society trembling in their uptight boots. And 18,000 of them are here to see the band kick off their 50 and Counting tour at LA's enormo sports-complex the Staples Center.

Home to the basketball's Lakers and Clippers, venue of the Grammys, and the site of Michael Jackson's very public memorial, the Staples Center is neither dangerous nor sexy. Yet when sprinkled with a hefty amount of Stones' stardust, it becomes the perfect place for the band to start their 17-show skulk across North America, ahead of their long-awaited Glastonbury Festival appearance in June and two huge Hyde Park shows in July.

Nearly every other person here seems to be sporting a Rolling Stones shirt of some description – be it boxfresh and studded with diamante, or tatty, torn and evidently worn on a weekly basis since 1972. The punters make for an interesting cross-section of modern America: families chowing down on pizza, middle-aged businessmen with glamorous younger companions, women in hotpants and heels working the Almost Famous vibe, elderly couples who've followed the band for years, and embarrassed-looking teenagers dragged along by giddy parents.

This being LA, there's also a liberal sprinkling of Hollywood stars, including Jack Nicholson – who gets a spontaneous standing ovation when he walks on to the floor to find his seat – David Hasselhoff, Pierce Brosnan, and – don't get too excited, now – Angel from Buffy.

Though many tickets for the evening came with a rather hefty $600 price tag, the band also released a number of limited $85 tickets, with fans only finding out on arrival where in the arena they'll be sitting. Lauren Gordon, 30, from Los Angeles, is outside in the 'cheap' ticket line. "I thought that it was great that they gave us the opportunity to buy these tickets for $85. I think they're going to put on a good show, even though they're old," she says.

Joe Pesanco, 64, and his wife Fran have been with the Stones from the start, attending shows at every single US tour the band has been on. "I've seen them for 50 years," says the Orange County resident with a grin. "We saw them when they first came to America," adds Fran. "I think it was '64 or '65 at the Philadelphia Academy of Music. When they first came out they seemed to be a little scared, not quite comfortable on stage. Now they are.

"Keith over the years has gotten more of a showman – I've started to like him and accept him as a Stone now, finally." Joe laughs: "She's very picky."

Despite reports on the day that the show hadn't yet sold out, by the time the band take to the stage there doesn't seem to be an empty seat in the house.

However, this is perhaps due to a last-minute release of 1,000 extra $85 tickets, some of which seem to be situated pretty close to the celebrity packed $600 blocks, suggesting that a judicious mark-down in price helped shift those final few seats.

Either way, the show is more of a success than the Rolling Stones' first US jaunt 49 years ago, which saw them arriving with no hits to their name and general dismay at their scruffiness. Former bass player Bill Wyman branded the tour a "disaster".

But scruffy is the last thing they are tonight. An outrageously slimline Mick Jagger – the 69-year-old's waist is about as wide as one of my thighs – pulls on a number of slinky shirts throughout the evening, and dons an epic, floor-length ostrich feather cape for Sympathy for the Devil. It may not get him many fans at Peta but it will certainly give the likes of Lady Gaga sartorial food for thought. The appearance of Gwen Stefani – lending her vocals and swishy platinum mane to Wild Horses – also ups the glamour factor significantly.

Sporting a Stones shirt and brandishing a margarita, Rebecca Crooks, 24, from Los Angeles, is here to see the band for the first time. "They're my favourite fucking band of all time. I've grown up listening to them," she says. "I might have a heart attack before Mick Jagger does."